The seabed and wrecks are dynamic environments. As divers we are not always aware of just how much things change unless something dramatic occurs. In 2012 the stern of the Karlsruhe was very ship-shape with neat lengths of teak decking in place. Then the stern winch capstan collapsed to the seabed and upended everything.
Anything moving messes up photogrammetry and recent experience with brittlestars has proved frustrating…but what if the entire structure of the wreck changes?
Here’s a chunk of the SMS Karlsruhe in glorious 3D:
While scanning this section new sections of bright orange rust were seen. This is a clear indication things are moving but without a baseline to compare we have no idea how much.
13 Years of Movement
Way back in 2006 a multi beam survey scanned the Karlsruhe. Would this help identify what was moving? Created by Prof. Chris Rowland at ADUS the multi beam results were perfect for a quick visual compare.
Firstly, the results from 2006:
And the same view of the wreck from 2019:
The red arrows indicate common features in each image. The steel section with rectangular cutouts has dropped from its 2006 position to now lie closer to the seabed. The davit in the top right of the frame has shifted too, now lying closer to the seabed.
Whilst the techniques and methods of multi beam sonar and photogrammetry differ both remain valuable and complimentary. A great way to visualise changes on the seabed. You can check out the multi beam sonar model of the Karlsruhe here.
One thing a wreck always needs is scale and preferably something everyone can relate to. The SMS Karlsruhe is no exception and in this chunk we have a very static Jacob resting on the seabed next to the wreck.
The ortho photo derived from the 3D model has some gaps and represents a small fraction of the wreck but its worth sharing the progress so far:
Here’s a zoomed in view of the ortho photo:
The ortho photo is not quite detailed enough to check if the cylinders in test, but we can tell Jacob was on a 20/02 air/helium mix for this dive.
The model includes part of the salvage break. Its a jumbled and confusing area if the visibility is less than ideal but the ortho photo of this area will reveal exactly what is there. Here’s a snip from the ortho photo:
And a really zoomed in view of the sea urchin centre right:
Back to the Source
The images shot back in April are still being worked through. The first step is to eliminate every single frame where Brittlestars dominate. We may be some time…